This invention relates generally to metallic cables, and more specifically to a cable structure suitable for reinforcing elastomeric articles and an apparatus and method for manufacturing a cable having this structure.
One of the problems that has been encountered with elastomeric articles that are reinforced with metallic cables is the propagation of corrosion along the length of the cable in the event that the article is cut or torn such that the reinforcing cable is exposed. One approach to solving the problem of corrosion propagation has been to make a very compact metallic cable, so that there are minimum interstices between the filaments comprising the cable which could serve as pathways for the spread of corrosion. A second approach has been to make a cable with a very open construction, so that the elastomeric material in which the cable is embedded can substantially surround each filament making up the cable. The present invention is concerned with the second approach.
U.S. Pat. Nos. 3,700,012 and 3,763,683 teach a method and apparatus for providing a cable comprising helically formed wire filaments that are nested in bundles and encapsulated in an elastomeric material to form a reinforced fabric. These patents teach a structure comprising wire filaments which are not twisted about one another and have no wrapping filament holding the helically formed filaments together, so this prior art structure must be immediately encapsulated in an elastomeric material as a part of the manufacturing process. The inability to store this prior art wire structure on spools means that each production line must comprise both a cable forming apparatus and an apparatus for encapsulating the cable in an elastomeric material such as a calender. Such a production line has the disadvantages that it is very expensive to manufacture, and may require an inordinately long set-up time between production runs.
A metallic cable according to the present invention may be collected and stored upon a spool, which eliminates the need for an in-line calender without twisting of the cable. Advantages of the present invention are: (a) efficient and low cost manufacturing of the metallic cable: (b) the capacity to provide a substantially flat cable to facilitate a thinner final product (such as conveyor belts): (c) better control of the spacing between filaments in the cable which reduces or eliminates fretting contact: and (d) better coverage of the filaments by elastomers which reduces corrosion in the final product.
There is provided in accordance with one aspect of the invention a metallic cable comprising a plurality of substantially identical metallic filaments formed into helixes, said plurality of filaments not being twisted about one another and not having any other filament wrapped thereabout, said plurality of filaments being adhered to one another by a plurality of applications of an adhesive substance, said applications being spaced apart from one another with respect to a longitudinal axis of said cable.
There is provided in accordance with another aspect of the invention a method of manufacturing a metallic cable comprising the steps of:
(a) providing a plurality of substantially identical metallic filaments formed into helixes:
(b) arranging said metallic filaments beside one another without twisting them about one another and without wrapping any other filament around said plurality of filaments: and
(c) applying an adhesive substance to said plurality of filaments in a plurality of locations that are spaced apart with respect to the longitudinal axis of said cable.
There is provided in accordance with yet another aspect of the invention an apparatus for manufacturing a metallic cable of the type disclosed herein comprising:
(a) a bobbin means for supplying a plurality of metallic filaments;
(b) a means for simultaneously deforming a plurality of metallic filaments by imparting a helical shape thereto;
(c) a reservoir for an adhesive substance, and a transfer mechanism for intermittently applying said adhesive to a metallic cable moving past said reservoir and transfer mechanism in a direction parallel to the longitudinal axis of said metallic cable;
(d) a spool means for collecting the cable; and
(e) a drawing means for pulling the filaments from said bobbin means, through the means for helically deforming the filaments, past the mechanism for applying an adhesive, and to said spool means.